272 REPORTS ON THE STATE OF SCIENCE.—IQI3. 
birth the eye has a volume equal to about half 
that of the full-grown eye; the materials of which 
it is built are comparatively soft and yielding; the 
functional power of the visual apparatus is merely 
a perception of light. By growth and develop- 
ment, rapid at first, slower later on, the eye tends 
progressively to acquire the dimensions and the 
powers of the normal completed organ. 
Nutrition by healthy blood, and the natural 
stimulus of voluntary use, are essential to this 
process. We know by experience that in early 
infancy disease may arrest the growth of the eye, 
and that suspension of use, as when a serious 
ophthalmia prevents an infant for many weeks from 
attempting to use its eyes, may check functional 
development to an extent which cannot after- 
wards be made good. On the other hand, exces- 
sive efforts, due to unnatural demands on the 
eyesight, are apt to be injurious in the opposite 
direction. Unfortunately there is evidence to show 
that the demand made on the eyesight of school 
children is not infrequently excessive. 
At the age when school life begins the visual 
apparatus is still immature. The orbits, the eyes 
themselves, and the muscles and nerves which move 
them, have still to increase considerably in size.. 
The various brain-structures concerned in vision 
have not only to grow but to become more complex. 
The intricate co-ordinating mechanism which 
later will enable the eyes, brain, and hand to work 
together with minute precision is awaiting develop- 
ment by training. ‘The refraction of the eyes is 
not yet fixed. It is usually more or less hyper- 
metropic, with a tendency to change in the direction 
of normal sight ; in other words, it has not reached 
the ideal condition in which the eyes see distant 
objects without accommodative effort, but is tend- 
